Step inside the Patriot Club fitness facility in Fairfax County. Try out the carpeted track, the racquetball courts, the silver-and-blue weight room. Then head for the gleaming locker area and have a sauna.

Not bad for a charitable organization.

Fairfax Board Chairman John F. Herrity was given a free membership when the club opened, and he jogs there about twice a week. "It's a great facility," he said. "They're far superior to a health club, except they're lacking a pool."

The one-eighth-mile indoor track is rough on the knees, said Herrity, but the quarter-mile outside track "is like running on your rug." The tracks at most health clubs, by contrast, are "like running in your living room," he said.

The Patriot Club expects to raise $185,000 this year for athletic scholarships at George Mason University. In exchange for annual tax-deductible dues of $300 to $600, members are entitled to use the two-year-old field house, which they share with the state-run school's 15,000 full- and part-time students.

To lure donors, colleges across the nation are offering more than the warm glow of doing a good deed. So contributors are given or are sold tickets on the 50-yard line, library privileges or -- in the case of George Mason and George Washington University in the District -- use of school athletic facilities.

"That's the new trend in fund-raising -- you get nothing for nothing," said Alan K. Srebnick, George Mason's director of development for athletics.

But the practice is being challenged by tax reform groups and the Internal Revenue Service, who contend that part or all of such donations may not be tax-deductible.

"If they require you to make a contribution to get something , it's not a contribution, it's a scam," said Robert S. McIntyre, the federal tax policy director for Citizens for Tax Justice.

The selling of university privileges is part of trend by many cash-strapped colleges to use their facilities to the fullest and reap the added income. Schools are renting dormitory rooms in summer, offering conference space and allowing outsiders to use their computer facilities.

"This is all part of a much broader picture," said Sheldon E. Steinbach, general counsel for the American Council on Education, a group representing 1,700 colleges and universities. "It's designed to maximize all kinds of facilities."

At George Washington University, a five-year, tax-deductible pledge of $1,000 buys member- ship in the President's Club, where athletic privileges can be added for $400 a year. The 210 members have their own locker room, sauna, steam room, color television and exercise area. They may use the Smith Center's pool, track, racquetball and squash courts and other facilities.

"More and more people -- especially our younger members -- are joining to get a workout," said John C. Harper, the club director. The tax-deductible donation supports the school's building fund. The dues pay for athletic programs.

At the University of Maryland, donors cannot buy athletic privileges, but they can join the Terrapin Club, which offers good seats at sports events and priority parking. For $100, they can join the university's Century Club and use the library.

American University offers no similar program, although officials say they may consider one when their new sports facility is completed. Georgetown University offers membership at Yates Field House, but the dues are not tax deductible.

Many big-name schools finance athletic programs by ticket sales and alumni donations, but George Mason is a relatively young college and its games are not sellouts. The school raises only a tiny portion of its money from alumni. So Srebnick, looking for "something that was a desirable item and conducive to the mission of the university," created the Patriot Club five years ago.

The club sponsors an annual golf tournament with a $175-a-day entry fee. It holds an outdoor crafts show that brings in $8,000 to $9,000. And it offers basketball tickets, key chains and a newsletter.

Srebnick says club membership became more attractive when the field house opened two years ago, influenced by the fitness boom and the higher fees charged by nearby profit-making health clubs; and it may gain even more when the university's new 10,000-seat arena opens, probably by fall. But Srebnick said, "I kind of hope that no matter why you're giving, you're giving because you think it's a good cause."

The IRS thinks so too, and spokesmen say the agency is prepared to enforce the distinction between a good cause and a good deal. Federal tax rules state that anything of value obtained in return for a donation reduces the amount of the donation that can be deducted from income taxes.

Someone who pays $100 to join a school booster club and gets $25 worth of tickets in return, for example, should deduct only $75 from federal taxes, according to the IRS.

In September, in a case that has implications for groups such as the Patriot Club, the IRS issued a ruling that cracked down on university booster clubs that offer a spot on the waiting list for choice seats at football games to people who give tax-deductible donations to an athletic scholarship fund. Donors got something of value, and therefore they could not deduct their entire contribution, the IRS said.

"There was a great uproar from the university community," IRS spokesman Steven J. Pyrek said. The IRS suspended the ruling, took the unusual step of holding a hearing on it in January, and has not yet decided whether to reissue it.

The IRS received 40 to 60 letters on the issue, all but five or six opposed to the ruling, Pyrek said. College officials have called the ruling unworkable, saying it is impossible to place a market value on the tickets obtained by booster club members, and that, in any case, those tickets are not always better than those the public can obtain.